Class: ProtocolBuffers::Message

Inherits:
Object
  • Object
show all
Defined in:
lib/protocol_buffers/runtime/message.rb

Overview

Generated Code

This text describes exactly what Ruby code the protocol buffer compiler generates for any given protocol definition. You should read the language guide before reading this document:

code.google.com/apis/protocolbuffers/docs/proto.html

Packages

If a package name is given in the .proto file, all top-level messages and enums in the file will be defined underneath a module with the same name as the package. The first letter of the package is capitalized if necessary. This applies to message and enum names as well, since Ruby classes and modules must be capitalized.

For example, the following .proto file:

package wootcakes;
message uberWoot { }

Will define a module Wootcakes and a class Wootcakes::UberWoot

Messages

Given a simple message definition:

message Foo {}

The compiler will generate a class called Foo, which subclasses ProtocolBuffers::Message.

These generated classes are not designed for subclassing.

Ruby message classes have no particular public methods or accessors other than those defined by ProtocolBuffers::Message and those generated for nested fields, messages, and enum types (see below).

A message can be declared inside another message. For example: message Foo { message Bar { } }

In this case, the Bar class is declared inside the Foo class, so you can access it as Foo::Bar (or if in package Baz, Baz::Foo::Bar)

Fields

For each field in the message type, the corresponding class has a member with the same name as the field. How you can manipulate the member depends on its type.

Singular Fields

If you have a singular (optional or required) field foo of any non-message type, you can manipulate the field foo as if it were a regular object attribute. For example, if foo‘s type is int32, you can say:

message.foo = 123
puts message.foo

Note that setting foo to a value of the wrong type will raise a TypeError. Setting foo to a value of the right type, but one that doesn’t fit (such as assigning an out-of-bounds enum value) will raise an ArgumentError.

If foo is read when it is not set, its value is the default value for that field. To check if foo is set, call has_foo? To clear foo, call message.foo = nil. For example:

assert(!message.has_foo?)
message.foo = 123
assert(message.has_foo?)
message.foo = nil
assert(!message.has_foo?)

Singular String Fields

String fields are treated like other singular fields, but note that the default value for string fields is frozen, so it is effectively an immutable string. Attempting to modify this default string will raise a TypeError, so assign a new string to the field instead.

Singular Message Fields

Message types are a bit special, since they are mutable. Accessing an unset message field will return a default instance of the message type. Say you have the following .proto definition:

message Foo {
  optional Bar bar = 1;
}
message Bar {
  optional int32 i = 1;
}

To set the message field, you can do either of the following:

foo = Foo.new
assert(!foo.has_bar?)
foo.bar = Bar.new
assert(foo.has_bar?)

Or, to set bar, you can simply assign a value directly to a field within bar, and - presto! - foo has a bar field:

foo = Foo.new
assert(!foo.has_bar?)
foo.bar.i = 1
assert(foo.has_bar?)

Note that simply reading a field inside bar does not set the field:

foo = Foo.new
assert(!foo.has_bar?)
puts foo.bar.i
assert(!foo.has_bar?)

Repeated Fields

Repeated fields are represented as an object that acts like an Array. For example, given this message definition:

message Foo {
  repeated int32 nums = 1;
}

You can do the following:

foo = Foo.new
foo.nums << 15
foo.nums.push(32)
assert(foo.nums.length == 2)
assert(foo.nums[0] == 15)
assert(foo.nums[1] == 32)
foo.nums.each { |i| puts i }
foo.nums[1] = 56
assert(foo.nums[1] == 56)

To clear a repeated field, call the clear method, or assign nil to it like a singular field.

foo = Foo.new
foo.nums << 15
foo.nums.push(32)
assert(foo.nums.length == 2)
foo.nums.clear
assert(foo.nums.length == 0)
foo.nums = nil # equivalent to foo.nums.clear
assert(foo.nums.length == 0)

You can assign to a repeated field using an array, or any other object that responds to each. This will replace the current contents of the repeated field.

foo = Foo.new
foo.nums << 15
foo.nums = [1, 3, 5]
assert(foo.nums.length == 3)
assert(foo.nums.to_a == [1,3,5])

Repeated fields are always set, so foo.has_nums? will always be true. Repeated fields don’t take up any space in a serialized message if they are empty.

Repeated Message Fields

Repeated message fields work like other repeated fields. For example, given this message definition:

message Foo {
  repeated Bar bars = 1;
}
message Bar {
  optional int32 i = 1;
}

You can do the following:

foo = Foo.new
foo.bars << Bar.new(:i => 15)
foo.bars << Bar.new(:i => 32)
assert(foo.bars.length == 2)
assert(foo.bars[0].i == 15)
assert(foo.bars[1].i == 32)
foo.bars.each { |bar| puts bar.i }
foo.bars[1].i = 56
assert(foo.bars[1].i == 56)

Enumerations

Enumerations are defined as a module with an integer constant for each valid value. For example, given:

enum Foo {
  VALUE_A = 1;
  VALUE_B = 5;
  VALUE_C = 1234;
}

The following Ruby code will be generated:

module Foo
  VALUE_A = 1
  VALUE_B = 5
  VALUE_C 1234
end

An exception will be thrown if an enum field is assigned a value not in the enum. Right now, this includes throwing an exception while parsing. This may change in the future to match the C++ behavior of treating it as an unknown tag number.

Extensions

Protocol Buffer extensions are not currently supported in this library.

Services

Protocol Buffer service (RPC) definitions are ignored.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(attributes = {}) ⇒ Message

Create a new Message of this class.

message = MyMessageClass.new(attributes)
# is equivalent to
message = MyMessageClass.new
message.attributes = attributes



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# File 'lib/protocol_buffers/runtime/message.rb', line 235

def initialize(attributes = {})
  @set_fields = []

  fields.each do |tag, field|
    if field.repeated?
      self.instance_variable_set("@#{field.name}", RepeatedField.new(field))
      @set_fields[tag] = true # repeated fields are always "set"
    else
      value = field.default_value
      self.__send__("#{field.name}=", value)
      @set_fields[tag] = false
      if field.class == Field::MessageField
        value.notify_on_change(self, tag)
      end
    end
  end

  self.attributes = attributes
end

Class Method Details

.define_field(otype, type, name, tag, opts = {}) ⇒ Object

:NODOC:



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# File 'lib/protocol_buffers/runtime/message.rb', line 421

def self.define_field(otype, type, name, tag, opts = {}) # :NODOC:
  raise("gen_methods! already called, cannot add more fields") if @methods_generated
  type = type.is_a?(Module) ? type : type.to_sym
  name = name.to_sym
  tag  = tag.to_i
  raise("Field already exists for tag: #{tag}") if fields[tag]
  field = Field.create(self, otype, type, name, tag, opts)
  fields[tag] = field
  field.add_methods_to(self)
end

.field_for_name(name) ⇒ Object

Find the field for the given attribute name. Returns a ProtocolBuffers::field



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# File 'lib/protocol_buffers/runtime/message.rb', line 365

def self.field_for_name(name)
  name = name.to_sym
  field = fields.find { |tag,field| field.name == name }
  field && field.last
end

.field_for_tag(tag) ⇒ Object

Equivalent to fields



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# File 'lib/protocol_buffers/runtime/message.rb', line 372

def self.field_for_tag(tag)
  fields[tag]
end

.fields ⇒ Object

Returns a hash of { tag => ProtocolBuffers::Field }



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# File 'lib/protocol_buffers/runtime/message.rb', line 354

def self.fields
  @fields || @fields = {}
end

.gen_methods! ⇒ Object

Generate the initialize method using reflection, to improve speed. This is called by the generated .pb.rb code, it’s not necessary to call this method directly.



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# File 'lib/protocol_buffers/runtime/message.rb', line 490

def self.gen_methods! # :NODOC:
  @methods_generated = true
  # these generated methods have gone away for now -- the infrastructure has
  # been left in place, since they'll probably make their way back in at
  # some point.
end

.optional(type, name, tag, opts = {}) ⇒ Object

:NODOC:



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# File 'lib/protocol_buffers/runtime/message.rb', line 437

def self.optional(type, name, tag, opts = {}) # :NODOC:
  define_field(:optional, type, name, tag, opts)
end

.parse(io) ⇒ Object

Shortcut, simply calls self.new.parse(io)



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# File 'lib/protocol_buffers/runtime/message.rb', line 295

def self.parse(io)
  self.new.parse(io)
end

.repeated(type, name, tag, opts = {}) ⇒ Object

:NODOC:



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# File 'lib/protocol_buffers/runtime/message.rb', line 441

def self.repeated(type, name, tag, opts = {}) # :NODOC:
  define_field(:repeated, type, name, tag, opts)
end

.required(type, name, tag, opts = {}) ⇒ Object

:NODOC:



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# File 'lib/protocol_buffers/runtime/message.rb', line 432

def self.required(type, name, tag, opts = {}) # :NODOC:
  define_field(:required, type, name, tag, opts)
  @has_required_field = true
end

.valid?(message) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/protocol_buffers/runtime/message.rb', line 462

def self.valid?(message)
  return true unless @has_required_field

  fields.each do |tag, field|
    if field.otype == :required
      return false unless message.value_for_tag?(tag)
    end
  end
end

Instance Method Details

#==(obj) ⇒ Object

Comparison by class and field values.



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# File 'lib/protocol_buffers/runtime/message.rb', line 330

def ==(obj)
  return false unless obj.is_a?(self.class)
  fields.each do |tag, field|
    return false unless self.__send__(field.name) == obj.__send__(field.name)
  end
  return true
end

#attributes=(hash = {}) ⇒ Object

Assign values to attributes in bulk.

message.attributes = { :field1 => value1, :field2 => value2 } -> message



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# File 'lib/protocol_buffers/runtime/message.rb', line 322

def attributes=(hash = {})
  hash.each do |name, value|
    self.send("#{name}=", value)
  end
  self
end

#clear! ⇒ Object

Reset all fields to the default value.



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# File 'lib/protocol_buffers/runtime/message.rb', line 339

def clear!
  fields.each { |tag, field| self.__send__("#{field.name}=", nil) }
end

#default_changed(tag) ⇒ Object 



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# File 'lib/protocol_buffers/runtime/message.rb', line 450

def default_changed(tag)
  @set_fields[tag] = true
  if @parent_for_notify
    @parent_for_notify.default_changed(@tag_for_notify)
    @parent_for_notify = @tag_for_notify = nil
  end
end

#dup ⇒ Object

This is a shallow copy.



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# File 'lib/protocol_buffers/runtime/message.rb', line 344

def dup
  ret = self.class.new
  fields.each do |tag, field|
    val = self.__send__(field.name)
    ret.__send__("#{field.name}=", val)
  end
  return ret
end

#each_unknown_field ⇒ Object

yields |tag_int, value| pairs



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# File 'lib/protocol_buffers/runtime/message.rb', line 478

def each_unknown_field # :nodoc:
  return unless @unknown_fields
  @unknown_fields.each { |tag_int, value| yield tag_int, value }
end

#fields ⇒ Object

Returns a hash of { tag => ProtocolBuffers::Field }



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# File 'lib/protocol_buffers/runtime/message.rb', line 359

def fields
  self.class.fields
end

#inspect ⇒ Object 



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# File 'lib/protocol_buffers/runtime/message.rb', line 398

def inspect
  ret = ProtocolBuffers.bin_sio
  ret << "#<#{self.class.name}"
  fields.each do |tag, field|
    ret << " #{field.name}=#{field.inspect_value(self.__send__(field.name))}"
  end
  ret << ">"
  return ret.string
end

#merge_field(tag, value, field = ) ⇒ Object

:nodoc:



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# File 'lib/protocol_buffers/runtime/message.rb', line 408

def merge_field(tag, value, field = fields[tag]) # :nodoc:
  if field.repeated?
    if value.is_a?(Array)
      self.__send__("#{field.name}=", self.__send__(field.name) + value)
    else
      self.__send__(field.name) << value
    end
  else
    self.__send__("#{field.name}=", value)
    @set_fields[tag] = true
  end
end

#merge_from(obj) ⇒ Object

Merge the attribute values from obj into this Message, which must be of the same class.

Singular fields will be overwritten, except for embedded messages which will be merged. Repeated fields will be concatenated.

Raises:

  • (ArgumentError) 


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# File 'lib/protocol_buffers/runtime/message.rb', line 304

def merge_from(obj)
  raise(ArgumentError, "Incompatible merge types: #{self.class} and #{obj.class}") unless obj.is_a?(self.class)
  for tag, field in self.class.fields
    next unless obj.value_for_tag?(tag)
    value = obj.value_for_tag(tag)
    merge_field(tag, value, field)
  end
end

#merge_from_string(string) ⇒ Object

Parse the string into a new Message of this class, and merge it into the current message like merge_from.



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# File 'lib/protocol_buffers/runtime/message.rb', line 315

def merge_from_string(string)
  merge_from(self.class.new.parse(string))
end

#notify_on_change(parent, tag) ⇒ Object 



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# File 'lib/protocol_buffers/runtime/message.rb', line 445

def notify_on_change(parent, tag)
  @parent_for_notify = parent
  @tag_for_notify = tag
end

#parse(io_or_string) ⇒ Object

Parse a Message of this class from the given IO/String. Since Protocol Buffers are not length delimited, this will read until the end of the stream.

This does not call clear! beforehand, so this is logically equivalent to

new_message = self.class.new
new_message.parse(io)
merge_from(new_message)



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# File 'lib/protocol_buffers/runtime/message.rb', line 285

def parse(io_or_string)
  io = io_or_string
  if io.is_a?(String)
    io = ProtocolBuffers.bin_sio(io)
  end
  Decoder.decode(io, self)
  return self
end

#remember_unknown_field(tag_int, value) ⇒ Object 



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# File 'lib/protocol_buffers/runtime/message.rb', line 472

def remember_unknown_field(tag_int, value)
  @unknown_fields || @unknown_fields = []
  @unknown_fields << [tag_int, value]
end

#serialize(io) ⇒ Object

Serialize this Message to the given IO stream using the Protocol Buffer wire format.

Equivalent to, but more efficient than

io << message

Returns io



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# File 'lib/protocol_buffers/runtime/message.rb', line 263

def serialize(io)
  Encoder.encode(io, self)
  io
end

#serialize_to_string ⇒ Object Also known as: to_s

Serialize this Message to a String and return it.



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# File 'lib/protocol_buffers/runtime/message.rb', line 269

def serialize_to_string
  sio = ProtocolBuffers.bin_sio
  serialize(sio)
  return sio.string
end

#set_value_for_tag(tag, value) ⇒ Object 



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# File 'lib/protocol_buffers/runtime/message.rb', line 385

def set_value_for_tag(tag, value)
  self.__send__("#{fields[tag].name}=", value)
end

#unknown_field_count ⇒ Object 



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# File 'lib/protocol_buffers/runtime/message.rb', line 483

def unknown_field_count
  (@unknown_fields || []).size
end

#valid? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/protocol_buffers/runtime/message.rb', line 458

def valid?
  self.class.valid?(self)
end

#value_for_tag(tag) ⇒ Object

Reflection: get the attribute value for the given tag id.

message.value_for_tag(message.class.field_for_name(:f1).tag)
# is equivalent to
message.f1



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# File 'lib/protocol_buffers/runtime/message.rb', line 381

def value_for_tag(tag)
  self.__send__(fields[tag].name)
end

#value_for_tag?(tag) ⇒ Boolean

Reflection: does this Message have the field set?

message.value_for_tag?(message.class.field_for_name(:f1).tag)
# is equivalent to
message.has_f1?

Returns:

  • (Boolean) 


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# File 'lib/protocol_buffers/runtime/message.rb', line 394

def value_for_tag?(tag)
  @set_fields[tag] || false
end